Horn projector



March 1, 1932. R. M. CRITCHFIELD I 1,847,754

HORN PROJECTOR Filed May 31, 1930 llmanloz ROBERT M CR/TCHF/ELD.

Patented Mar. 1, 1932 UNITED s'ra'ras PATEN'D OFFICE I ROBERT M. CRIT'CHFIELD, OF ANDERSON, INDIANA, ASSIGNOR TO DELCO-REMY COR- PORATION, OF ANDERSON, INDIANA, A CORPORATION OF DELAWARE HORN PROJECTOR Application filed May 31,

.5 tone horn.

It is one of the objects of the instant inven- 7 'tion to provide'a sound product closely approaching the timber of a cornet or bugle. A further object of the instant invention 10 is to increase the effective length of the sound conduit.

A further object of the invention is to provide a purer air tone by damping. out objectionable mechanical sounds. 3

Further objects and advantages of the presentinvention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of one form of the present invention is clearly shown.

In the drawings:

Fig. 1 is a longitudinal sectional view of an improved trumpet including the instant invention.

Fig. 2 is a transverse sectional view thereof, substantially as indicated by the line and arrows 22 of Fig. 1.

With particular reference to the drawings, 20 indicates a collar member forming part of the housing of a magnet motor device of the usual vibratory horn, and in the illus trated embodiment provides a machined surface 21 for cooperation with a vibratory member or piston 23 secured to the armature rod 24 of the magnet motor, by anut 25 and lock washer 26. The magnet motor is not illustrated in full, but as is well known to those skilled in the art, the magnet motor operates to reciprocate the piston member 23 to and from the face 21 whereby rapid stopping of an air column is accomplished.

Secured to the collar member 20 in any desirable manner, there is a trumpet or projector provided with a clamping nut 31 that. may be threaded into the collar 20 as generally indicated at 32. The projector 30 terminates in a bell 33 that operates with the 7 face 21 to define an air column particularly responsive to the sound waves set up within the trumpet by the operating magnet moconvenient 1930. Serial No. 458,611.

tor. In sounding signals of the illustrated type, it is desired to produce a tone product of low pitch, and that, necessitates an elongated projector, but since a sounding signal device with a long projector is more expensive in manufacture, less convenient I to mount, and is of less. desirable appearance, means have been provided for increasing the effective length thereof without increase of its physical dimension. Due to the method of stopping the air column within the trumpet30, and due to the closeness of adjustment that must'be maintained between the piston 23 and face 21 of the collar member, there is apt to be present in the sound product of the signal device, mechanical noises that are frequently amplified by the projector 30, and it is therefore desirable to dampen out'those mechanical noises so as to purify the tone of the signal device and to better simulate a true air tone.

These problems have been solved in the instant invention, by providing the trumpet 30 with a spiral ribbon 40 forming a partition throughout the greater portion of its length, and dividing the air column into a pair of substantially gyratory paths 41 and 42. The ribbon 40 is inserted within the projector as illustrated so that the edges of the ribbon are in contact with the side walls of the trumpet where they. may be secured in any desirable manner as by soldering orthe like. In the illustrated. embodiment the spiral partition stops shortof the bell 33 as illustrated "at 43, and the trumpet. is spun outwardly to form a rib orridge at 44 at a ribbon and foraminous grill or screen 45. The grill prevents the entrance of foreign material within the projector'and operates to provide a more pleasing appearance than would otherwise obtain.

hen a soundingdevice is fitted with the improved, projector the sound waves impressed thereon will be'conducted along the throat of the projector where they will engage the spiral partition 40, and thus be conducted along either one of the gyratory paths 41 or 42 and thence outwardly in the'usual manner.

point between theend 43 of the the bell 33, so as to receive a This of course, increases the eilective length of the air column within the projector, in that the sound waves are caused to follow a longer path by reason of the spiral partition, then they would otherwise do without it. The partition member within the trumpet tends to load the same and thus reduces its fundamental of vibration, and thence the same is less responsive to high pitch mechanical vibmti on sset up by the 'vibr at ory mea us.

While the form-of en'ibodimento't the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

miat is claimed is as follows:

1. In a sounding device the combination comprising, an uninterrupted sound conduit, and means dividing the air column therein intoa pair of gyratory paths increasing the effective length ofsaid conduit.

2. The combination comprising,

a sound conduit, means supporting the conduit and operating therewith to define an column of vdefinite length, and means .divid ng the conduit into a 'ilurality of substantially parallel branches to increasetheeffective length ofisaid air'column.

3. Thecombination comprising, a sound conduit, means supporting the conduit and operating therewith todefine an air column of definitellength,;and means .forcingthe sound waves through said conduit to follow a pluralityofnyratorypaths whereby the effective length of-said conduit increased.

4. The combination comprising a sound conduit,means supporting theconduit and operatingtherewith to definean air column of definitejlength. and means dividing the air column into, a pair of gyratorv paths, whereby the effective lengththereof is increased.

'5. Thecombination comprising, a sound conduit,imeans sunporting the conduit and operating therewith to define an air column of definite length,,atwisted ribbon within the conduit for increasingthe effective length of the same.

6. The combination comprising, a sound conduit, 'means supporting the conduit and providing means for settinv: the air column thereby defined into audible vibration, and means carried by the sound conduit in creasing the effectivelength thereofand dampin out mechanical sounds, said last means comprisingia partitionmember dividing the said air column into a pair of substantialy helical sound paths.

7 rThe'combination comprising, a sound conduit, 1neans supporting the conduitand providing means-for setting the air column thereby defined into audible vibration, a twistedribbon dividing the air column into a pair of gyratory paths, said ribbon operatmg to increaseithe efilective length of said air 

